Portable heater



FIG. 1 is a right side front perspective view of a portable heater showing my new design;

FIG. 2 is a left side rear perspective view thereof;

FIG. 3 is a front elevation view thereof;

FIG. 4 is a right side elevation view thereof;

FIG. 5 is a left side elevation view thereof;

FIG. 6 is a rear elevation view thereof; and,

FIG. 7 is a top plan view thereof.

The broken lines illustrate portions and environmental structure of the portable heater and form no part of the claimed design. 

CLAIM The ornamental design for a portable heater, as shown and described. 